1. Technical Field
The following description relates to one or more image forming devices with a carrying unit such as a belt unit for carrying a recording medium such as a paper is detachably attached thereto.
2. Related Art
In order to make it easy to maintain a carrying belt for carrying a paper, for example, as disclosed in Japanese Patent Provisional Publication No. 2002-328571 (hereinafter referred to as '571 Publication), there has been proposed such a configuration that a belt unit with a carrying belt incorporated thereinto is detachably attached to a device main body.
However, when the belt unit is detached from the device main body by a user for the maintenance of the carrying belt, the maintenance might be completed despite the belt unit being not attached back to the device main body as a result of user's fault.
To solve the above problem, in the invention disclosed in '571 Publication, the presence of the belt unit can be checked with a reflective optical sensor configured to detect the density of an image transferred to the carrying belt.